This invention relates to a process for decolorizing polyethylene polyamines using a chlorinated hydrocarbon.
During their production and storage, it is well-known that the polyethylene polyamines, particularly the higher polyamines, become discolored. Heretofore, various processes have been suggested to overcome the problem of discoloration of polyethylene polyamines. One such method, as described in UK No. 1,351,050 comprises reacting an aqueous solution of hydrochloric acid or an amine hydrochloride with the discolored polyethylene polyamines and distilling the resulting mixture to obtain decolored polyethylene polyamines. European Pat. No. 0,058,962 describes an alternative process in which an aqueous hydrochloric acid solution is reacted with the discolored polyethylene polyamines and the resulting mixture is flash evaporated to obtain decolored polyethylene polyamines. Unfortunately, in both processes, water is introduced into the reaction system by the addition of the aqueous acidic solution. This requires an extra processing step to remove the added water from the process thereby increasing costs and capital expenditure.
Alternative prior art processes for decolorizing the discolored polyethylene polyamines include treatment with activated carbon at elevated temperatures (about 200.degree. C.); treatment with potassium hydroxide; and treatment with zinc metal, zinc metal and water or zinc metal and an alkali. Unfortunately, in each of these procedures, neutralization of residues, handling and separation of metal powders or reactivation of the treatment medium require special apparatus which complicate the process.
In view of the stated deficiencies in the prior art, it would be advantageous to develop an improved process for decolorizing discolored polyethylene polyamines which does not exhibit these deficiencies.